Ok, this is just too weird?
If i drive the car under 60 mph it is fine, if i take it past 60 mph it starts vibrating the entire car?
I am planning on checking the tires and rims this weekend but could it be anything else?
Thanks!

CG

 

Driveshaft.

 

tie-rods, balljoints, etc... Is it coming from the front end, or the rear?

If you can isolate the vibration location, you'd be in a better position to get some feedback from other forum members.

 

Is the first time you noticed it? Some drive shaft use to do that and many switched over to LS1 shafts or other aluminum shafts. However if it never has done it before, it may be your tires.JMHO

 

i'd say you're out of alignment

 

would cause vibration?
Another vote for driveshaft or bent wheel.

 

As far as i can tell its coming from the back?
I was always told that if you feel it in the steering wheel its the front end and if you feel it in the seat of your pants its the body/back end but i am not sure if that is true?

forgot too mention...it just started, it did not do this before.

 

Sounds like it isn't the front end.

Could be
Transmission
Driveshaft
Rear Axle
Rear wheels/Tires/ballance

Rotate your rear tires to the front and see if that changes where you feel the vibration.

 

is it mainly when you accelerate or decel? i had a problem like that but i got hit at a higher mph, and foun dout the pinion nut backed off and my yoke was loose and vibrated like crazy. it was there a lil when accelerating above 70, but it was the worst on decel.

 

Could be a whole host of things:

Tires out of balance
Bent wheels
Driveshaft
U-joints
Pinion angle
Trans Tailshaft bushing
Pinion bearing
Torn trans mount
Worn out torque arm bushing
Worn front suspension bushings ball joints etc

The list gets a lot longer, but its usually one of those. If its been more than about 20k since the tires were balanced and rotated I would start there.